The overall goal of the research is to determine if the expression of different classes of structural genes (nuclear vs. organelle) or the levels of different classes of enzymes (anabolic vs. catabolic; cytoplasmic vs. organelle) are regulated differently during the cell cycles of normal and cancer cells. If differences do exist, the plan is to design in a logical manner, drugs which will preferentially inhibit the proliferating cancer cells. Equilibrium (isopycnic) centrifugation will be used to select synchronous animal cells from asynchronous cultures for use in induction and derepression studies during the cell cycle. This same technique will be employed to isolate auxotrophic mutants and intact subcellular organelles. The change in the maximum rate of induced or derepressed synthesis of different enzymes, in relation to the timing of replication of the nuclear DNA and the satellite DNA species, will be used to determine the intracellular location of different structural genes. Differential inhibitors of DNA, RNA, and protein synthesis will be used to distinguish between the replication of nuclear and organelle DNA replication, and the site of synthesis and translation of different mRNA species. A highly compartmentalized eucaryotic microorganism also will be used as a model system for studying regulation of gene expression and enzyme levels during the cell cycle of eucaryotes.